Instructions

Mix onions, vinegar, lemon juice, sugar and pinch of salt in small bowl. Set aside for 15 to 30 minutes.
Mix yogurt, dill and ground pepper in another small bowl and set aside.
Toast or broil 7-grain or party pumpernickel bread until crisp. Cool.
Spread lightly with butter if using. Divide yogurt mixture evenly on bread slices. Divide salmon evenly on top of yogurt. Drain onions. Divide evenly on top of salmon. Sprinkle with capers. Serve.